Exploring the properties of dust in the Galaxy using X-ray spectroscopy
Sascha Zeegers
X-ray absorption fine structures reveal a wealth of information about interstellar dust. These features near X-ray absorption edges are an excellent tool to investigate the dust properties in the Galaxy, e.g. chemical composition, crystallinity and grain size. X-ray binaries are used as background lights to analyse the intervening dust along several Galactic sightlines. In the last decade the SPEX code has been expanded with a new dust model, based on an extensive laboratory campaign to measure the spectra of interstellar dust analogues [Costantini & De Vries 2013]. This allowed the exploration of dust in the central part of the Galaxy [e.g. Zeegers 2019, Rogantini 2020], as well as several diffuse sightlines [Psaradaki 2021]. The upcoming XRISM and Athena observatories call for a refinement of the dust models, because they cover the high energy part of the X-ray band at high spectral resolution. We will, for instance, be able to measure dust extinction features in such detail that we can derive dust size distributions and we can study the iron K-edge and the sulfur K-edge in great detail [Costantini et al. 2019, Zeegers et al. in prep]. This talk gives an overview of future explorations of dust features using the unprecedented high energy resolution of upcoming facilities.